Dwarf Bunt!

Challenges! No crop gives producers more chances to solve challenges than the wheat crop. The latest in the series, in the snow belt areas? DWARF BUNT!

There should not be dwarf bunt in this wheat crop! Virtually all seed was treated with Dividend, the only product that controls soil borne dwarf bunt. Yet some locations are reporting dwarf bunt in much of the wheat being delivered. Bunt, at low levels. Unfortunately, the tolerance for that "rotten fish" smell that bunt balls produce is: ZERO!

Why do we have bunt? Seed treatment is not perfect. A recent study by the Middlesex Soil and Crop Improvement Association drives this point home.

Dwarf bunt is "rate sensitive" to Dividend (see table 1). Dr. Walker Kirby, an expert on dwarf bunt in the U.S., suggests a minimum application rate of 100 ppm on each and every seed to give bunt control. The "target" rate, with the low label rate of Dividend, is 120 ppm/seed. That doesn't leave much room for error!

Source: R.H. Johnston, Montana State University

Source: MSCIA Crop Projects

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Source: Pratley, Dow and Johnson

Table 2 clearly shows that even if the cutoff for dwarf bunt control is 50% of the target, or 60 ppm/seed, low levels of bunt can be expected when lowest label rates are applied. Despite best efforts by seed treaters, current technology is not getting the job done. Wheat producers in the dwarf bunt area need better!

The results of table 3 support this conclusion. While differences between varieties 1, 2 and 4 exist, none meet the zero tolerance that exists for dwarf bunt. Only variety 3, with double the Dividend rate, gave acceptable control.

The bottom line? Talk to your seed supplier. If you grow wheat in the dwarf bunt area, there is no choice but to increase the rate of Dividend. Cost? Another $5.00/acre. Who should pay? Now that ought to be an interesting argument .…!

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